This invention relates to refrigerant compressors forming part of air conditioning systems for vehicles, and more particularly to a vane compressor which has a suction connector and a discharge connector arranged at a rear portion thereof.
Vane compressors are widely used in air conditioning systems for vehicles for compressing the refrigerant, by virtue of their structural simplicity and high adaptability to high speed operation. A typical vane compressor of this kind is generally constructed such that a front head is secured to a front side block which forms a pump housing in cooperation with a cam ring and a rear side block, the front side block and the front head being penetrated by a drive shaft, and the front head is formed therein with a sealing chamber in which a seal means is accommodated to seal the drive shaft against the front head. The front head is further formed therein with an annular suction chamber which also serves to cool the seal means in the sealing chamber, which is heated by rotation of the drive shaft. To this end, a suction port, through which refrigerant is introduced into the suction chamber, is formed in the front head.
In many vehicles in which such vane compressors are to be installed, a pump for power steering of the vehicle and/or a generator is placed at a front side of the compressor, providing difficulties in securing a sufficient space for accommodating a suction refrigerant hose connected to the suction connector having a suction port formed therethrough.
To avoid such difficulties, it has conventionally been proposed to arrange the suction connector and the discharge connector at a rear portion of the compressor. According to an example of such arrangement, a rear suction chamber is provided in addition to the aforementioned annular suction chamber on the front side, which is arranged at a rear side of the rear side block, whereby suction refrigerant is introduced into the rear suction chamber through the suction port in the rearwardly arranged suction connector, and then is sucked into pump working chambers defined within the pump housing, through rear pump inlets formed through the rear side block. However, this arrangement is devoid of means for cooling the aforementioned sealing chamber heated by the hot seal means.
In order to cool the sealing chamber, an arrangement has been proposed, in which all refrigerant introduced through the rearwardly located suction port is guided into the annular suction chamber on the front side, by way of a passage. However, according to this alternative arrangement, all the suction refrigerant travels through the above passage which inevitably extends through the ambience of hot discharge refrigerant, so that the suction refrigerant is heated and swelled as it travels through the passage, resulting in degradated volumetric efficiency of the refrigerant. Further, the discharge refrigerant has an increased temperature to cause a drop in the refrigerating efficiency. In addition, the travelling distance of suction refrigerant from the suction port to pump working chambers is large, spoiling the suction efficiency.